On 2018-12-03 15:16, Daniel P. Berrangé wrote: > On Mon, Dec 03, 2018 at 03:05:31PM +0100, Thomas Huth wrote: >> So far we only had implicit requirements for the minimum compiler version, >> e.g. we require at least GCC 4.1 for the support of atomics. However, >> such old compiler versions are not tested anymore by the developers, so >> they are not really supported anymore. Since we recently declared explicitly >> what platforms we intend to support, we can also get more explicit on the >> compiler version now. The supported distributions use the following version >> of GCC: >> >> RHEL-7: 4.8.5 >> Debian (Stretch): 6.3.0 >> Debian (Jessie): 4.8.4 >> OpenBSD (ports): 4.9.4 >> FreeBSD (ports): 8.2.0 >> OpenSUSE Leap 15: 7.3.1 >> Ubuntu (Xenial): 5.3.1 >> macOS (Homebrew): 8.2.0 >> >> So we can safely assume GCC 4.8 these days. For Clang, the situation is >> a little bit more ambiguous, since it is sometimes not available in the >> main distros but rather third party repositories. At least Debian Jessie >> uses version 3.5, and EPEL7 for RHEL7 uses 3.4, so let's use 3.4 as >> minimum Clang version now - we still can adjust this later if necessary. >> >> Signed-off-by: Thomas Huth <th...@redhat.com> >> --- >> configure | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/configure b/configure >> index 0a3c6a7..f1e305e 100755 >> --- a/configure >> +++ b/configure >> @@ -1840,6 +1840,25 @@ if test "$bogus_os" = "yes"; then >> error_exit "Unrecognized host OS (uname -s reports '$(uname -s)')" >> fi >> >> +# Check whether the compiler matches our minimum requirements: >> +cat > $TMPC << EOF >> +#if defined(__clang_major__) && defined(__clang_minor__) >> +# if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 4) >> +# error You need at least Clang v3.4 to compile QEMU >> +# endif > > NB although this will succeed, it is not technically checking the > right thing on macOS platforms as their clang used a completely > different numbering scheme. It just happens to have larger numbers > than upstream clang, so we'll always succeed.
Does that only apply to the version string that is reported by "clang --version" or does it also apply to the __clang_major/minor__ macros? In the latter case, I think I could add a comment to the patch here. I'm also not sure whether the LLVM version necessarily matches the Clang version? In older versions, you can also see "4.2 (clang-425.0.28) (based on LLVM 3.2svn)" in the tables there... > IOW, to require clang >= 3.4 on macOS, we would need to require > their version >= 5.1 If they also messed up the macros, I think we likely have a problem the other way round: What upstream Clang version corresponds to the Apple Clang version 3.4 ? ... but if I interpret the old table right, they just started the confusion with 5.0, so I think the check above should still be fine. Thomas
